I can send email and can't receive. 553 Relaying disallowed

I can send email and can't receive. 553 Relaying disallowed

Hi,

Testing from zoho to gmail -> all works
testing from gmail to zoho returns the error below.
May I please ask if you could assist me on this issue?

The response was:
553 Relaying disallowed
Final-Recipient: rfc822; info@bosphor.......
Action: failed
Status: 5.0.0
Remote-MTA: dns; mx.zoho.eu. (31.186.226.32, the server for the domain bosphor.......)
Diagnostic-Code: smtp; 553 Relaying disallowed
Last-Attempt-Date: Thu, 25 May 2017 00:47:37 -0700 (PDT)